Study on Catalytic Performance and Deactivation Behavior of HZSM-5 in Aromatization of Glycerol

We have investigated both the catalytic performance and deactivation behavior of HZSM-5 under aromatization of glycerol condition which represents an alternative aromatics manufacturing route for using "green" fuel sources to replace the traditional fossil fuels. The effects of solvents, glycerol contents, reaction temperature and weight hourly space velocity (WHSV) on product distribution and coking process over HZSM-5 were studied. Three stages could be clearly distinguished in HZSM-5 catalyzed glycerol to aromatics (GTA) process: induction stage, auto-catalytic stage and rapid deactivation stage. The synergetic effect between methanol and glycerol promoted the conversion of glycerol dehydrated products into aromatic hydrocarbons, resulting in higher yields of aromatics and lower coking rate. More glycerol content in the feed would result in more low temperature coke originated from aldehydes/ketones and less high temperature coke derived from polyaromatics. Under the selected optimum reaction conditions of 450 degrees C, WHSV= 0.71 mL.g(-1) .h(-1) with an methanol/glycerol ratio of 40/60 over HZSM-5 catalyst, the aromatics yields reached 42.1% and the catalyst lifetime was 14.5 h. Higher temperature and lower WHSV benefited the production of harder coke while lower temperature and higher WHSV enhances the formation of softer coke.